Examinando por Autor "Lorenz, R. D."

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Acceso Abierto
Lander and rover histories of dust accumulation on and removal from solar arrays on Mars
(Elsevier, 2021-11-01) Lorenz, R. D.; Martínez, Germán M.; Spiga, A.; Vicente Retortillo, Álvaro; Newman, C. E.; Murdoch, N.; Forget, F.; Millour, E.; Pierron, T.; National Aeronautics and Space Administration (NASA); Agence Nationale de la Recherche (ANR); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The degradation in electrical output of solar arrays on Mars landers and rovers is reviewed. A loss of 0.2% per Sol is typical, although observed rates of decrease in ‘dust factor’ vary between 0.05% and 2% per Sol. 0.2%/Sol has been observed throughout the first 800 Sols of the ongoing InSight mission, as well as the shorter Mars Pathfinder and Phoenix missions. This rate was also evident for much of the Spirit and Opportunity missions, but the degradation there was episodically reversed by cleaning events due to dust devils and gusts. The enduring success of those rover missions may have given an impression of the long-term viability of solar power on the Martian surface that is not globally-applicable: the occurrence of cleaning events with an operationally-useful frequency seems contingent upon local meteorological circumstances. The conditions for significant cleaning events have apparently not been realized at the InSight landing site, where, notably, dust devils have not been detected in imaging. Optical obscuration by dust deposition and removal has also been observed by ultraviolet sensors on Curiosity, with a similar (but slightly higher) degradation rate. The observations are compared with global circulation model (GCM) results: these predict a geographically somewhat uniform dust deposition rate, while there is some indication that the locations where cleaning events were more frequent may be associated with weaker background winds and a deeper planetary boundary layer. The conventional Dust Devil Activity metric in GCMs does not effectively predict the different dust histories.
Acceso Abierto
The dynamic atmospheric and aeolian environment of Jezero crater, Mars
(Science Publishin Group, 2022-05-25) Newman, C. E.; Hueso, R.; Lemmon, M. T.; Munguira, A.; Vicente Retortillo, Álvaro; Apéstigue, Víctor; Martínez, Germán M.; Toledo, D.; Sullivan, Robert; Herkenhoff, K. E.; De la Torre Juárez, M.; Richardson, M. I.; Stott, A.; Murdoch, N.; Sánchez Lavega, Agustín; Wolff, Michael; Arruego, I.; Sebastián, E.; Navarro López, Sara; Gómez Elvira, J.; Tamppari, L. K.; Smith, Michael D.; Lepinette Malvitte, A.; Viúdez Moreiras, Daniel; Harri, Ari-Matti; Genzer, María; Hieta, M.; Lorenz, R. D.; Conrad, Pamela G.; Gómez, Felipe; McConnochie, Tim H.; Mimoun, D.; Tate, C.; Bertrand, T.; Belli, J. F.; Maki, Justin N.; Rodríguez Manfredi, J. A.; Wiens, R. C.; Chide, B.; Maurice, S.; Zorzano, María-Paz; Mora Sotomayor, L.; Baker, M. M.; Banfield, D.; Pla García, J.; Beyssac, O.; Brown, Adrian Jon; Clark, B.; Montmessin, F.; Fischer, E.; Patel, P.; Del Río Gaztelurrutia, T.; Fouchet, T.; Francis, R.; Guzewich, Scott; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Ciencia e Innovación (MICINN); Ministerio de Economía y Competitividad (MINECO); Agencia Estatal de Investigación (AEI); Gobierno Vasco; National Aeronautics and Space Administration (NASA); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Despite the importance of sand and dust to Mars geomorphology, weather, and exploration, the processes that move sand and that raise dust to maintain Mars’ ubiquitous dust haze and to produce dust storms have not been well quantified in situ, with missions lacking either the necessary sensors or a sufficiently active aeolian environment. Perseverance rover’s novel environmental sensors and Jezero crater’s dusty environment remedy this. In Perseverance’s first 216 sols, four convective vortices raised dust locally, while, on average, four passed the rover daily, over 25% of which were significantly dusty (“dust devils”). More rarely, dust lifting by nonvortex wind gusts was produced by daytime convection cells advected over the crater by strong regional daytime upslope winds, which also control aeolian surface features. One such event covered 10 times more area than the largest dust devil, suggesting that dust devils and wind gusts could raise equal amounts of dust under nonstorm conditions.
Acceso Abierto
The sound of a Martian dust devil
(Nature, 2022-12-13) Murdoch, N.; Stott, A. E.; Gillier, M.; Hueso, R.; Lemmon, M. T.; Martínez, Germán M.; Apéstigue, Víctor; Toledo, D.; Lorenz, R. D.; Chide, B.; Munguira, A.; Sánchez Lavega, Agustín; Vicente Retortillo, Álvaro; Newman, C. E.; Maurice, S.; De la Torre Juárez, M.; Bertrand, T.; Banfield, D.; Navarro López, Sara; Marín, M.; Torres, J.; Gómez Elvira, J.; Jacob, Xavier; Cadu, A.; Sournac, A.; Rodríguez Manfredi, J. A.; Mimoun, D.; National Aeronautics and Space Administration (NASA); Centre National D'Etudes Spatiales (CNES); NASA Jet Propulsion Laboratory (JPL); Comunidad de Madrid; Gobierno Vasco; Agencia Estatal de Investigación (AEI); Los Alamos National Laboratory; Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Dust devils (convective vortices loaded with dust) are common at the surface of Mars, particularly at Jezero crater, the landing site of the Perseverance rover. They are indicators of atmospheric turbulence and are an important lifting mechanism for the Martian dust cycle. Improving our understanding of dust lifting and atmospheric transport is key for accurate simulation of the dust cycle and for the prediction of dust storms, in addition to being important for future space exploration as grain impacts are implicated in the degradation of hardware on the surface of Mars. Here we describe the sound of a Martian dust devil as recorded by the SuperCam instrument on the Perseverance rover. The dust devil encounter was also simultaneously imaged by the Perseverance rover’s Navigation Camera and observed by several sensors in the Mars Environmental Dynamics Analyzer instrument. Combining these unique multi-sensorial data with modelling, we show that the dust devil was around 25 m large, at least 118 m tall, and passed directly over the rover travelling at approximately 5 m s−1. Acoustic signals of grain impacts recorded during the vortex encounter provide quantitative information about the number density of particles in the vortex. The sound of a Martian dust devil was inaccessible until SuperCam microphone recordings. This chance dust devil encounter demonstrates the potential of acoustic data for resolving the rapid wind structure of the Martian atmosphere and for directly quantifying wind-blown grain fluxes on Mars.